Study Of Virtual Vibration Measurement And Analysis System

In modern mechanical industry and mechanical engineering, vibration measurement and analysis is an important part. With the development of computer and software technique, virtual instrument become development direction in measurement field, vibration measurement and analysis based on virtual instrument has become the trend of vibration test. So author develop virtual instruments of multichannel vibration measurement and analysis system based on PC as hardware workbench, laboratory virtual instrument workbench (LabVIEW) developed by America National Instruments corporation as development software, essential sensor, signal conditioner and data acquisition card. The system can control data acquisition, processing and display in computer, to meet the demand of vibration measurement and analysis.First, simple introduction on virtual instruments is made in my thesis. Second, the composition of vibration measurement system and the theory of vibration signal analysis are analyzed. Last, the measurement identification of the developed system is made. This system can run in Microsoft Windows 98, and data acquisition, storage, processing and display adopt modularization program. The data sampling include two kind: free sampling adapted to random signal and pretrigger sampling adapted to impact signal. The signal process function of the software include these function: digital filter, windowing, auto-correlation function and cross-correlation function, mean and variance, probability density function and probability distribution function statistic; auto-power spectrum, cross-power spectrum, frequency response function, coherence function, cepstrum analysis based on FFT(Fast Fourier Transfer); joint time-frequency analysis based on STFT(Short-Time Fourier Transfer).In this research of vibration measurement and analysis virtual instruments, data acquisition card based on expanding slot of PC and LabVIEW software are applied to the virtual measurement system. The experiment result has proved that the method has good expansibility and high cost performance, easy to develop, be fit for use of engineer.